21277: Keep fleet desktop running when host is offline (#30493)

For #21277 

Show offline message on Fleet Desktop if host is offline.

orbit/changes/21277-offline-indicator

@@ -0,0 +1 @@
+* Added feature for showing an informational message on fleet desktop if host becomes offline.

orbit/cmd/desktop/desktop.go

@@ -175,6 +175,14 @@ func main() {
 
 		myDeviceItem := systray.AddMenuItem("Connecting...", "")
 		myDeviceItem.Disable()
+		myDeviceItem.Hide()
+
+		hostOfflineItem := systray.AddMenuItem(
+			`🛜🚫 Your computer is offline.
+
+It might take up to 5 minutes to reconnect to Fleet.`,
+			"")
+		hostOfflineItem.Disable()
 
 		selfServiceItem := systray.AddMenuItem("Self-service", "")
 		selfServiceItem.Disable()
@@ -220,12 +228,17 @@ func main() {
 		disableTray := func() {
 			log.Debug().Msg("disabling tray items")
 			myDeviceItem.SetTitle("Connecting...")
+			myDeviceItem.Show()
 			myDeviceItem.Disable()
+
 			transparencyItem.Disable()
 			selfServiceItem.Disable()
 			selfServiceItem.Hide()
+
 			migrateMDMItem.Disable()
 			migrateMDMItem.Hide()
+
+			hostOfflineItem.Hide()
 		}
 
 		reportError := func(err error, info map[string]any) {
@@ -283,8 +296,13 @@ func main() {
 					if err == nil || errors.Is(err, service.ErrMissingLicense) {
 						log.Debug().Msg("enabling tray items")
 						myDeviceItem.SetTitle("My device")
+						myDeviceItem.Show()
 						myDeviceItem.Enable()
+
 						transparencyItem.Enable()
+						transparencyItem.Show()
+
+						hostOfflineItem.Hide()
 
 						// Hide Self-Service for Free tier
 						if errors.Is(err, service.ErrMissingLicense) || (summary.SelfService != nil && !*summary.SelfService) {
@@ -345,21 +363,28 @@ func main() {
 				sum, err := client.DesktopSummary(tokenReader.GetCached())
 				switch {
 				case err == nil:
-					// OK
+					hostOfflineItem.Hide()
 				case errors.Is(err, service.ErrMissingLicense):
 					myDeviceItem.SetTitle("My device")
+					myDeviceItem.Show()
+					hostOfflineItem.Hide()
 					continue
 				case errors.Is(err, service.ErrUnauthenticated):
 					disableTray()
+					hostOfflineItem.Hide()
 					<-checkToken()
 					continue
 				default:
+					myDeviceItem.Hide()
+					transparencyItem.Disable()
+					hostOfflineItem.Show()
 					log.Error().Err(err).Msg("get desktop summary")
 					continue
 				}
 
 				refreshMenuItems(sum.DesktopSummary, selfServiceItem, myDeviceItem)
 				myDeviceItem.Enable()
+				myDeviceItem.Show()
 
 				// Check our file to see if we should migrate
 				var migrationType string

orbit/cmd/orbit/orbit.go

@@ -955,6 +955,10 @@ func main() {
 			return fmt.Errorf("error new orbit client: %w", err)
 		}
 
+		// If the server can't be reached, we want to fail quickly on any blocking network calls
+		// so that desktop can be launched as soon as possible.
+		serverIsReachable := orbitClient.Ping() == nil
+
 		// create the notifications middleware that wraps the orbit client
 		// (must be shared by all runners that use a ConfigFetcher).
 		const (
@@ -1043,18 +1047,20 @@ func main() {
 			orbitClient.RegisterConfigReceiver(extRunner)
 		}
 
-		// Run a early check of fleetd configuration to check if orbit needs to
-		// restart before proceeding to start the sub-systems.
+		// Run an early check of fleetd configuration (iff server can be reached)
+		// to check if orbit needs to restart before proceeding to start the sub-systems.
 		//
 		// E.g. the administrator has updated the following agent options for this device:
 		//	- `update_channels`
 		//	- `extensions` were removed/unset
 		//	- `command_line_flags` (osquery startup flags)
-		if err := orbitClient.RunConfigReceivers(); err != nil {
-			log.Error().Msgf("failed initial config fetch: %s", err)
-		} else if orbitClient.RestartTriggered() {
-			log.Info().Msg("exiting after early config fetch")
-			return nil
+		if serverIsReachable {
+			if err := orbitClient.RunConfigReceivers(); err != nil {
+				log.Error().Msgf("failed initial config fetch: %s", err)
+			} else if orbitClient.RestartTriggered() {
+				log.Info().Msg("exiting after early config fetch")
+				return nil
+			}
 		}
 
 		addSubsystem(&g, "config receivers", &wrapSubsystem{
@@ -1094,12 +1100,14 @@ func main() {
 				return fmt.Errorf("initializing client: %w", err)
 			}
 
-			// Check if token is not expired and still good.
-			// If not, rotate the token.
-			expired, _ := trw.HasExpired()
-			if expired || deviceClient.CheckToken(trw.GetCached()) != nil {
-				if err := trw.Rotate(); err != nil {
-					return fmt.Errorf("rotating token: %w", err)
+			// Check if the token is not expired and still good.
+			// If not, rotate the token iff the server is reachable.
+			if serverIsReachable {
+				expired, _ := trw.HasExpired()
+				if expired || deviceClient.CheckToken(trw.GetCached()) != nil {
+					if err := trw.Rotate(); err != nil {
+						return fmt.Errorf("rotating token: %w", err)
+					}
 				}
 			}